The ability of the cell to maintain the stability of its genome is critical for survival, and eukaryotic cells are constantly challenged by both exogenous and endogenous sources of DNA damage. Cells are particularly susceptible to DNA damage during replication, when replication-blocking lesions can lead to collapse of a replication fork and formation of a double-strand break. As a result, cells have finely tuned processes to repair DNA damage during replication and to stabilize and restart forks that have stalled during DNA replication. Importantly, defects in these processes have been linked to a growing number of human diseases, among which are a number of syndromes associated with congenital and developmental defects as well as a predisposition to cancer. The overall objective of the studies proposed here is to identify and characterize new pathways and proteins involved in maintaining genomic integrity and replication fork stability. We recently conducted an unbiased genome-wide siRNA screen in human cells to identify candidate genes involved in these processes. Amongst our screening hits are many genes with no previously known connections to genome stability pathways. Here, we propose a series of additional assays to identify novel effectors of replication fork stability among our candidates. The unbiased approach we have taken has the potential to reveal unexpected connections between genome stability and other cellular processes, and to define new mechanisms by which cells maintain genome stability. Thus, we anticipate that these experiments will open novel avenues of investigation. PUBLIC HEALTH RELEVANCE: Defects in DNA damage response pathways have been linked to a growing number of human diseases, among which are a number of syndromes associated with a predisposition to cancer as well as congenital and developmental defects. Thus, the proteins and processes that we may link to replication fork stability could be responsible for some of these disease, and the knowledge gained from understanding the signaling pathways linked to these syndromes could provide critical insights relevant to their diagnosis, treatment and etiology. [unreadable] [unreadable] [unreadable] [unreadable]